The 2wayair system by Rock Smasher Engineering allows inflation or deflation of all tires simultaneously

If there’s one thing that all RVers can agree upon, it’s that checking and adjusting tire pressure on the tow vehicle and trailer is a pain in one’s backside. Without a doubt, proper tire-inflation pressure is critical to safe RV travel, and tire manufacturers typically recommend that inflation pressure be checked and adjusted before and during travel. But getting down on one knee and moving around a truck and trailer with a gauge and an air hose — if you can even find a source for compressed air — is a time-consuming process at best; in extreme temperatures, it can become downright uncomfortable. If you’ve got a dually and a tandem- or triple-axle trailer, we don’t need to tell you how long the process takes — and if you routinely air up or down to travel off-road, you’ve likely invested in a pair of kneepads and a stool by now.

The fact is, as much as we all hate having to constantly check and adjust tire pressure, no one has come up with a more convenient way to do it — until now. Rock Smasher Engineering (RSE) is a start-up company founded by a group of engineers who have designed suspensions for everything from road-race motorcycles to off-road trucks. As off-road enthusiasts themselves, they worked for several years to develop a system that would make it easier to air-up and -down when traveling off-road and created a product they call 2wayair. 2wayair is a universal fit central manifold system that allows users to inflate or deflate all tires on the vehicle at the same time using polyurethane tubing, nylon ties, specially designed Schrader valves and an assortment of push-to-connect fittings. The idea behind 2wayair is that it fits any vehicle (just specify four, six or eight tires), installs with a minimum amount of tools and can be used quickly in a harsh off-road environment. Here’s how the system works: The 3/8-inch manifold tubing runs along either side of the vehicle. It T’s into smaller ¼-inch tubing that runs to each corner of the vehicle where one of the kit’s Schrader valves is mounted. Once the system is plumbed, all the user needs to do is connect “whips” with quick-connect fittings to the Schrader valve on the tire and the vehicle, and inflate all tires at once using a central inflation point, which can be located anywhere you want (common choices are under the hood and front bumper). The system balances the pressure in all tires during inflation, so even if one tire is higher or lower than the others, they all inflate to the same pressure. And because the system is not pressurized unless an air source is connected and the connection points are closed, there’s no danger of losing pressure out of the tires if one of the lines were to become severed.

The system’s design is at once simple and sophisticated. For example, the central inflation point is a common Schrader valve, but all kits also come with a mini control valve that can be fitted with a common male D-type connector (the same used on compressed air lines) so you have the option of inflating with an air hose, an air/CO2 tank or whatever. Polyurethane tubing was chosen instead of the more common nylon for several reasons. First and foremost, it’s flexible and can’t kink. Second, this particular tubing is food grade, meaning it is manufactured to a much higher standard than industrial tubing. Finally, it’s very easy to work with and cut, which makes it possible to install or repair the system anywhere. To keep installation simple, all fittings are push-to-connect — there are no hose clamps. The tubing itself can be fastened with two different varieties of UV-rated nylon ties: standard and mountable. The mountable ties have small anchors that push into an existing or predrilled 3/16-inch hole; simply push the anchor into place, insert the manifold tubing and zip it closed. RSE even supplies sections of hard polyethylene tubing to protect the manifold tubing wherever it is mounted, so there are no concerns over chafing. Last, but certainly not least, anyplace the manifold tubing passes through metal is bulkheaded, so the polyurethane never makes contact with sharp edges.

(6) Here the main control panel is shown mounted under the hood with the supplied hardware, just below the onboard air compressor. Now the rest of the system is ready to be plumbed.

Realizing that the system could be used on anything from a short wheelbase Jeep to a tag-axle motorhome, RSE designed 2wayair to be modular so the base system can be custom tailored to the application and/or upgraded with a variety of available accessories. One of the most popular options is a liquid-filled, vibration-resistant air-pressure gauge kit and a pressure-relief valve that can be preset at the factory to the tire’s inflation pressure. Simply connect an air source, or in the case of an onboard air compressor, just open the valve. When the air pressure reaches the set point on the relief valve, the valve makes a loud “burping” noise. This is the valve bleeding off excess air, which prevents overinflation of the tires. Disconnect the whips, and you are ready to travel. There are also a variety of mounting brackets available so all accessories can be mounted in one place, or individually.

RSE offers its 2wayair kits for four wheels (cars, trucks and vans), six wheels (duallies and motorhomes) and eight wheels (tag-axle motorhomes). And recently, the company released kits for single-, double- and triple-axle trailers, as well as a jumper hose that will connect the 2wayair system on the tow vehicle to the one on the trailer. By using separate valves and connecting/disconnecting whips, it is possible to inflate the tires on the tow rig and trailer to different pressures.

(9) Dually kits use a male D-type connector at the rear. First, a Unibit is used to drill a .790-inch hole in the rocker panel near the tires, then a D-type push-to-connect bulkhead adapter is installed using a nut on the other side. (10) The male D-type fitting is then installed into the bulkhead adapter and tightened. Typically, a female fitting is used on the supply side of an air system, but here a female D-type connector is more likely to become clogged with dirt and debris. A male fitting has no moving parts, and the plastic cap keeps dirt out. (11) Here is the rear D-type fitting (with cap) and adapter, with the 3/8-inch polyurethane manifold tubing pushed into place.

To test the 2wayair system, we contacted RSE and requested a six-tire master kit ($319.95) to be mounted on a 2000 Dodge Ram extended cab dually. Because this particular truck carries a camper and occasionally ventures off road, RSE also recommended a pressure-relief valve ($24.95), pressure-relief valve mounting kit ($29.95), onboard air kit (enables the system to be connected to an onboard air system, $44.95), 160 psi gauge kit ($84.95) and a master control panel ($12.95), bringing the grand total to $517.70. Considering the convenience afforded by this system (which will likely outlast the vehicle), that’s a pretty reasonable price. Since no shop space was available for this project, it was installed on the truck right in the storage parking lot, proving RSE’s claim that the system can be installed pretty much anywhere. Installation took roughly three hours, and once connected, it worked as promised. We had only a couple of minor problems: The pressure-relief valve required minor adjustment to bypass at the tire’s 80 psi preset, and we soon found out that the onboard air pump was not up to the task of continuous duty and had to be replaced. The 2wayair system is an innovative solution to an age-old problem. Once you try it, you’ll never air-up your vehicle’s tires the “old” way again.

(12) The main 3/8-inch manifold tubing is run along an existing wiring loom and secured with supplied nylon ties. The stiff polyethylene tubing is used to cover the manifold tubing to prevent chafing wherever a tie is used. Alternately, the manifold tubing can be secured by drilling 3/16-inch holes along the plumbing route and the mountable cable ties used. The polyurethane tubing has a temperature limit of 160 degrees, so make sure to route it away from heat sources. The 3/8-inch manifold tubing is then cut near the front wheel, and the 3/8-inch to 1/4-inch T installed (arrow). The 1/4-inch tubing is routed to the front Schrader valve mounted earlier. (13) Here you can see the route from the main 3/8-inch manifold tubing to the T-fitting and the 1/4-inch tubing running to the front Schrader valve. The process is then repeated on the other side of the vehicle. (14) All of the manifold tubing converges at the control panel under the hood. The 3/8-inch manifold tubing from either side of the vehicle is tied to the main control valve with a 3/8-inch T-fitting. All of the peripherals — i.e. the gauge, the Schrader valve, the pressure relief valve and the onboard air line — T into the main manifold. It’s easier to install than it is to explain, believe us. The air compressor was then plumbed into the system with a male D-type quick-disconnect fitting and 1/4-inch FIP by 1/4-inch OD push-to-connect adapter. The user now has three options for airing-up (female D-type from an air hose, the Schrader valve or the onboard air compressor that is plumbed in).

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